A refrigerant evaporator functions as a cooling heat exchanger that cools fluid (for example, air) flowing outside by evaporating refrigerant (liquid phase refrigerant) flowing inside to absorb heat from the fluid.
A refrigerant evaporator includes first and second evaporation units, each of which has a heat-exchanging core portion formed by stacking multiple tubes and a pair of tank portions connected to both ends of the multiple tubes. The first and second evaporation units are disposed in series in a flow direction of the fluid, and first tank portions of the respective evaporation units are coupled to each other via communication portions (see, for example, PTL 1).
The refrigerant evaporator of PTL 1 is configured in such a manner that when refrigerant that has flowed the heat-exchanging core portion of the first evaporation unit is made to flow into the heat-exchanging core portion of the second evaporation unit via the first tank portions of the respective evaporation units and a pair of the communication portions coupling the first tank portions, flows of the refrigerant are interchanged in a width direction (right-left direction) of the heat-exchanging core portions. In other words, the refrigerant evaporator is configured in such a manner that the refrigerant flowing the heat-exchanging core portion of the first evaporation unit on one side in the width direction is made to flow into the heat-exchanging core portion of the second evaporator portion on the other side in the width direction using one of the pair of communication portions, while the refrigerant flowing the heat-exchanging core portion of the first evaporation unit on the other side in the width direction is made to flow into the heat-exchanging core portion of the second evaporation unit on the one side in the width direction using the other communication portion.